Prior art circuitry measures the available line voltage supplied to an appliance by employing a comparator on a microprocessor that compares the line voltage to a referenced voltage. An example of such circuitry is disclosed in U.S. Pat. No. 5,212,360, issued to Carlson on May 18, 1993. This device provides direction to automatically switch multi-rated internal components of an appliance to accommodate the detected line voltage supplied to that appliance. The electrical components within the appliance are provided with multiple connections for various potential line voltages thus allowing the automatic switching to match the measured line voltage.
Additional prior art measures the available line voltage as disclosed in the '360 Patent but does not automatically switch internal components. These circuits notify the user of the magnitude of the available line voltage but require manual switching of the appliance's electrical components.
There is not found in the prior art a circuit that automatically and accurately matches the required voltage to each component using an analog to digital converter (ADC) by routing one leg of a heater supply through the ADC.